This invention relates to roof drain inserts and more particularly to a coupling device to sealably secure a roof drain insert inside a drain pipe.
Roof drains are located in roofs of buildings to remove water from rain and melted snow therefrom. Resurfacing and repair of roofs is necessary from time to time. For example, conventional flat top asphalt roofs typically require resurfacing every 10 to 20 years. Frequently in resurfacing an existing roof, the height of the roof may be increased above that of existing roof drains, in which case, steps must be taken to ensure that water may drain from the new roof surface into the drains without entering new layers which may have been added to the roof. For example, at the time of resurfacing an existing roof, the insulative properties of the roof may wished to be increased so as to minimize heat transfer therethrough with resultant energy savings in heating and air conditioning. Adding insulative layers on top of an existing roof may significantly increase the roof height.
Where the height of the roof is increased a drain insert or extension may be required to raise the height of an existing roof drain to the height of the new roof surface so as to ensure that no water may pass between the edge of the existing drain and new layers added to the roof.
A recent development in resurfacing of roofs involves the use of sheet material to provide a new water proof layer for the roof. Such sheeting may comprise rolls of polyvinyl chloride plastic sheeting or APDM rubber sheeting which are rolled over the roof and joined together as by gluing and heat welding so as to form a continuous fluid impermeable layer. Such sheetings are not typically secured to the roof except at the their periphery and should water be permitted to get between the old roof and new sheeting, the water may flow out therebetween over the entire surface of the roof without restriction.
Entrance of water into newly added insulative layers or under new sheet material providing a new water proof layer is to be appreciated as potentially damaging, as for example, where the insulative value of the insulation may be impaired by the presence of the water therein and where possible structural damage may result with freezing.
To date, to extend an existing drain pipe, a simple drain insert with a lower portion thereof having a diameter less than the diameter of the drain pipe has been inserted axially inside the existing drain pipe. To seal the drain insert inside the drain pipe, adhesives or caulking compounds have been placed around the outside of the drain insert prior to insertion in the hope that a seal may be formed with the drain pipe. Even when particular care and time may be taken by a conscientious workman, known drain inserts suffer the disadvantage that there can be no guarantee that a seal may be formed between the drain insert and the existing drain pipe. Furthermore, such a seal as may be achieved by caulking compounds has the disadvantage of being insufficient to withstand water pressures as may be developed. The problem of water backing-up in a roof drain is not uncommon. When a roof drain may become totally blocked, or may have an inadequate flow capacity to remove a sudden accumulation of water, water may back-up in the drain to the roof with a resulting water pressure head acting on the caulking seal which the caulking cannot withstand. On even partial failure of the caulking seal, water is free to travel into the newly added roof layers, causing possibly damage and destruction.
To secure a drain insert to the roof, lag screws or long nails typically have been attempted to be extended from the top of the new drain insert through the newly added layers so as to engage a structural portion of the roof. In practise it is very difficult to ensure that the new drain insert may be securely fixed in place. Often times, there may be no convenient structural portion of the roof close to the drain insert to which the insert may be efficiently and effectively secured.
Drain inserts which are not securely fixed to a structural portion of the roof suffer the disadvantage that they have at least limited mobility and, with the passage of time, the seal between the drain insert and the new water proof layer of the roof is likely to become impaired.